Support for the electrodes of electron discharge devices



N 1949 G. w. BAKER 2,489,850

SUPPORT FOR THE ELECTRODES OF ELECTRON DISCHARGE DEVICES Filed March 9, 1948 y i'za /06 22 2 I04 I07 22 103 /4 INVENTOR.

GEORGE w. BAKER A T TORNEY electron emitting cathode will not be deactivate Patented Nov. 29, 1949 UNITED time SUPRORT: FOR THE ELEGTRQDES 1 0E" ELECTBQN DISQHARGEDEWGES:

G W a e FlliWEti Application March .9; 1948; SexialwNm 5 Qa aa attend.

and, to accomplish this end, the anod :1

ls usu ally supported by the glass envelope p lgyeddfron one end thereof, and the catho is mounted by a stem or header carried at th opposite end of the tube. The cycle. of operatigna of (131111: g, which electrons fiow from the cathode to the anode and current is delivered to the load; minimum voltage drop, and a blocking, p. rfi od whe'n the voltage across the tube electrod is 'high and reversed, and little or no current new the reverse direction, The peak value 01 reverse voltage applied tothe tube is, of course, known as the inverse peak voltage.

when the inverse peak voltage is extremely,

ub s hut; bothhave eenzfennd u satisfa m: The mica disks underlngh'temperature continue. qusly, nmduca. agas; while the metal springs. nder. high. temperature, take 1 a; permanent settand; snbseouentlie exer ano .press.ure.; against the; Hill l; Smiace of: he envelopelto ,holdtthe, anode;

n. plate-- 01 f;- the. principal-ix obleetsv: oi the present? nten ion theref re, isatmp'royideya simple,anti; m ant anode. upport which will. neither D203; 1. 9 as.-.I.1or pemanentlyzl se its: resilien y as esn tx tiexposure tel-mien temperatures, with'the; r swtrtha th rou hrdegassingtot'theanode (lure m lm nuiactureeot:the tube effected.

rectifier tube includes a conductingperiod l t Anethen-obieclt 0t thelmventiou is to. m ri 4. 1 QQtEOdB support. which-twill be .small in sizm nd economical tomanufaeture;

A f f l-1&1 biecttoirtheinvention-is to provide; n lr 1fi.- um0l1t:whiiihesatlsfies.therequiree llfi fifii i anflntire yrrcliable; lowicost'. small sizeshie avqltageireetinemube.-

n a ther. obiectfnistneimention iStOz-Dlfiflg; ide temperatu e chan e responsive: means. for

educing. m pro lmmsm; in an :electron. .dischama high, for example of the order of from 10 to tuba.

kiloiiolt s, special precautions must be taken prevent the reverse flow of current by cold field m pnf electrons m he. oqewhisht a n the; dxawingsrforminaapant oftthiaipatent aa app ication;

1isan xploded persneetivetviem.showingt he: am assem lm maegi ai serupn. mm.

39. pa t ally om denvelona 14... Thorough degassing of the. anode greatly re by liberated gas and can therefore be operated at a value near its initial maximum value.

In one of the supporting arrangements'now in I use"; a comparatively large diameter, rigid metal' lic"m'ember is fastened to the anode and sealed. through the glass envelope. The disadvantages" for this method include relatively great expense, the objection that more space than can be spared ing-agsmall glass envelope is required, and lack'of uniformity in heating the anode. Sheet. micadislgs and metal springs have. also. been usedi asll WPQ EW onth an s fthigh oltagerectifi 35 Midlife v t'icatsec mnanview meme. lin -i elevati theianede; supportingv springer. dn nonti nsldisplaced :flTQMe. he willl iithe,

ation.

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'nz mpl' lli pl ni mt M inre tieac memn a es-jovem m n the one. le ti nstin erent:intpre en athodalsupnort qmed ina-gmi r a tube; toia. comparativelyz. small diameter-wires hich erves san electricah connection .to .said ano e..- and atr-the same timei-preventsr it 7. from; marina xiallmt alonettherenvelopel Theanode;

5 is nonnal ly heldiin its ptopex operative..positione.

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loci/rout. ube. cone; safi mctlon' ethods bx, fastemn itheanode. of zthegt in the envelope by bimetallic spring fingers fastened to said anode and having end portions which, at normal temperatures, bear against the envelope wall. As the temperature increases, during the anode degassing operation, the behavior of the bimetallic spring fingers changes; first, without changing their shape, they relax their pressure on the wall of the envelope. Subsequently, and as the temperature is further increased, the spring fingers again change their shape to the extent that their end portions move out of engagement with the envelope wall. Thus,

although the fingers are heated. to a high temperature during the anode degassing'operation, they are in inoperative positions andv will not assume a permanent set. After the anode de- 22a and 22c of the fingers 22 again in engage- 'ment with the envelope wall in anode centering gassing operation is completed, and the temper'ature of the anode and the spring fingers is returned to normal, the said fingers will again assume their original shapes, when their end portions will bear against the envelope wall for retaining the anode in place.

In Fig. l of the drawings a partially completed vacuum tube is shown at I0. The tube I0 is preferably of glass and includes a cylindrical envelope II, open at its lower end, and a sealing ofi stem I2. The anode assembly is indicated generally at I 3 and includes a cylindrical anode I4 having rolled'upper and lower rims I5 and I6. The anode is supported from the top" of the envelope II by a conductor II formed of the well known *Dumet wire, said conductor engaging, at its lower end, the mid-portion of a bail I8 which extends transversely of and is secured to the upper end of said anode. A bead of glass I9, to combine with the glass ofthe envelope during the sealing operation, is carried on the conductor H, and a transversely disposed wire stop is welded to saidconductor beneath the bead to limit downward movement of the assembly. A getter H of conventional arrangement is secured to'the-conductor IT above the bail I8.

The spring fingers normally operative for mounting the anode in the envelope I I are shown at 22. Inasmuch as said fingers are of identical formation and composition," a description of one will suffice for all. Three fingers 22 are shown but it should be understood that a greater or less number can be used, if desired. Typically, one ofupper rim l5 thereof, the upper mid-portions of said fingers being of substantially greater length than said lower mid-portions and constituting resilient envelope engaging portions 22a. ,The

upper end portions of the fingers 22 are directed inwardly, as at 22b, to permit easy insertion of the anode assembly into the envelope. The lower ends of the fingers are bent outwardly to "define lower envelope engaging portions 220. r The portions 22a and 220 will cooperate to prevent longitudinal wobbling of the anode in the envelope.

=. In Fig. 2 of the drawings the anode assembly I3 is'shown in the inverted, partially completed en-- velope II, with the. portions 22a and 220 of the fingers 22 in engagement with the inner surface and supporting positions. The completed tube includes, of course, the anode terminal cap 24,

the cathode assembly 25 and the button, or base, .26.

It is desired to call attention to the fact that the spring fingers 22 are mounted on the anode at the end thereof most remote from the cathode so as to be out of the electric field during the blocking period (period of high inverse peak voltage) of the cycle of operation of the tube.

To illustrate another use to which bimetallic springs may be used in the manufacture of electron discharge tubes, the structure of Fig. 6 has been included. In this view an envelope somewhat similar to the envelope II is shown at WI. The envelope IOI is closed at its lower end by a base I02. Mica electrode supporting disks are shown at I03 and I04. A cathode I05, comprising the usual nickel or nickel alloy tube, appropriately coated to provide electron emission when heated, is supported at its upper end by the mica I03. A heater I06, energizable to bring the oathode to the operating temperature of approximately 1000 K., is conventionally contained in said cathode. As will be understood, the length of the cathode will increase appreciably as it is brought up to operating temperature. For this reason it can be rigidly secured only at one end, as by the mica I03. The other end must be received freely through the mica I04 if buckling is to be prevented. This free mounting of one end of the cathode causes electro-mechanical noise commonly known as microphonism.

To overcome microphonism caused by inadequate cathode support, I provide a collar I01 which surrounds the cathode near its lower end. The collar I0! is, like the fingers 22, of bimetallic material (nickel and iron) and has integrally formed spring fingers I08 which project through the central opening in the mica. Electrical connection from the cathode prong of the tube to the lower end of the cathode is made by a flexible metal member I09. It will be understood that the temperature of the collar I01 and fingers I08 will be raised as the cathode reaches operating temperature, with the result that the springs will expand for rigidly mounting the lower end of said cathode in the mica I04, whereby microphonism caused by improper cathode support will be eliminated.

It should be understood that, while I have described my invention as applied to anode and cathode supports for electrode discharge devices, ithas other applications too numerous to mention.

I claim:

1. An electron discharge device having an en velope, and an anode in the envelope, means supporting the anode in the envelope and including a conductor, a stop on the conductor for preventing displacement of the anode in the envelope during the degassing of said anode, and normally resilient means supporting the anode in the envelope, said last mentioned means being deformable from supporting position by the effect of raising the anode to high temperature and being restorable to supporting position by lowering the anode temperature.

2. An electron discharge device as recited in claim 1, wherein said last mentioned means consists of a bimetallic spring finger.

3. An electron discharge device as recited in claim 1, wherein said last mentioned means consists of a plurality of bimetallic spring fingers secured to the anode and having portions normally bearing against the wall of the envelope.

4. An electron discharge device having an envelope, a cathode in the envelope, a heater for the cathode, and means rigidly mounting one end of the cathode, means freely receiving the opposite end of the cathode, and a bimetallic spring finger extending between the cathode and said last mentioned means and responsive to temperature changes on said cathode for restraining the lower end of said cathode against lateral movement.

5. An electron discharge device having an envelope, a cathode in the envelope, a heater for raising the cathode to operating temperature, and a support rigidly mounting one end of the cathode, a disk having an opening freely receiving the opposite end of the cathode, and a collar surrounding the cathode and. having fingers engaging said disk, said collar and fingers being of bimetallic material responsive to temperature changes on the cathode and restraining the low- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,194,281 Doane Aug. 8, 1916 1,550,768 Weinhart Aug. 25, 1925 2,078,371 Daene Apr. 27, 1937 2,093,567 McCollough Sept. 21, 1937 2,094,654 Hirmann Oct. 5, 1937 2,116,224 Sternberg May 3, 1938 2,178,836 Krahl Nov. 7, 1939 2,178,837 Krahl Nov. 7, 1939 2,380,496 Beard July 31, 1945 OTHER REFERENCES The Electronic Control Handbook, by Batcher and Moulic, published by Caldwell Clements Inc. (1946), pp. 99 through 102. 

